1. Field
The present disclosure relates to an optical fiber and, more particularly, to a single-mode optical fiber with a large effective area that exhibits a low attenuation loss and a low bending loss and that has a broad wavelength range of operation, and a method of manufacturing the same.
2. Description of the Related Art
In wavelength division multiplexing (WDM) systems, several channels with different wavelengths of signals are multiplexed onto a single optical fiber. As the number of channels in the WDM system increases, more optical power has to be carried by the single optical fiber. Accordingly, nonlinear optical effects, such as non-linear scattering, four-wave-mixing, self-phase modulation, cross-phase modulation, and so on, caused by interaction between the channels becomes more significant. Optical fibers having a large effective area have been developed to reduce these non-linear effects in long haul transmission of information. Large effective area optical fibers allow the transfer of a large number of signals by reducing the density of the optical power in the single optical fiber.
In a large effective area optical fiber, an electromagnetic field in an optical fiber is expanded from the core portion of the optical fiber to an outer cladding portion of the optical fiber as compared to a standard single-mode optical fiber (SSMF) as defined in Telecommunication Standardization Sector of International Telecommunication Union (ITU-T) G.652. Thus, as the distribution of the electromagnetic field is spread over the optical fiber, a macrobending loss increases significantly. As used in the present disclosure, “macrobending loss” refers to a bending-induced excess loss as the optical fiber is physically bent as compared to “microbending loss” that refers to a loss that is randomly applied within the fiber such as may occur on a small scale if sandpaper is run over the optical fiber.
The macrobending loss may be suppressed by introducing a trench into the outer cladding portion, where the trench has a lower refractive index compared to the cladding portion. As the refractive index of the trench becomes lower, the macrobending loss becomes lower. However, as the refractive index of the trench becomes lower, it is necessary to dope more down-doping dopant in the optical fiber at the trench. This increased dopant causes the manufacturing process to become more complex and costly.
Additionally, as noted above as the effective area of the optical fiber increases, the macrobending loss performance of the fiber decreases. Thus, it is difficult to produce an optical fiber that has good macrobending loss characteristics (i.e., a low macrobending loss) while also having a large effective area.